Not applicable.
Not applicable.
1. Field of the Invention
The invention relates to the field of heat sealing caps to containers. In particular, the invention relates to air cooled sealing heads.
2. Discussion of the Prior Art
It is known to seal the mouths of bottles and other containers using an inductive sealing process. Inductive sealing requires an electromagnetic-field-producing apparatus and a foil-polymer seal. Typically, the apparatus has at least one coil of wire wound to produce an electromagnetic field when electric current is supplied to the coil. It is well known in the art that electromagnetic fields induce eddy currents within metal which in turn heat the metal. The seal comprises a thin layer of aluminum foil onto which is laminated a polymer layer that is molecularly compatible with the container to be sealed. When the seal is placed onto the container and the container is placed within the electromagnetic field, the foil is heated which melts the layer of polymer. Removing the seal from the electromagnetic field allows the polymer to cool and molecularly fuse with the container to create an air-tight seal.
The electromagnetic field strength primarily depends upon the number of turns in the wire coils and the amount of current supplied to the coils. To produce an electromagnetic field adequate for commercial inductive sealing, typically the power supply must output power in the order of a few kilowatts, which produces a great deal of heat. Thus, the power supply must be cooled in order to function properly. Similarly, the sealing head having the induction coil must be cooled.
Many methods of cooling the power supply and sealing head are known in the art. In particular, it is known to circulate cool water through the power supply enclosure and the sealing head. Such water cooled cap sealers, however, require complicated piping configurations that increase size and cost. It is also known to vent the power supply and force air past the outside of the sealing head. However, such air cooled cap sealers sometimes provide inadequate cooling of the sealing head which degrades the operating efficiency of the cap sealer.
The invention provides a ventilated sealing head for an inductive cap sealer. Specifically, the sealing head includes an induction coil for producing an electromagnetic field. One or more field focusing elements are disposed adjacent the coil to direct the electromagnetic field of the coil toward a sealing region beneath the sealing head. The coil and the field focusing elements are contained in a housing having openings allowing air to flow past the coil.
In a preferred form, the field focusing elements are a ferromagnetic compound and there are a plurality of field focusing elements spaced apart along at least a portion of the periphery of the coil allowing air to flow between the spaced field focusing elements and past the coil.
In other forms, the housing forms a tunnel extending lengthwise from side to side of the sealing head and opening downward at the sealing region. The coil is wound around the tunnel and within a number of electromagnetic field focusing elements. The sealing head further includes a pair of plug-in shielded connectors for coupling the coil to power.
Another aspect of the invention is a cap sealer having an AC power supply and an external vented sealing head as described above. The cap sealer can further include an external fan disposed between the sealing head and the power supply for forcing cooling air through the sealing head.
The invention thus provides a vented sealing head for an inductive cap sealer. Venting the sealing head allows cooling air to be blown passed the coil and field focusing elements to carry away heat from these components and convectively cool the sealing head. The sealing head can thus be cooled without a separate cooling circuit and without the costly and difficult to assemble tubing arrangements associated with liquid cooling.
The foregoing and other advantages of the invention will appear from the following description. In that description reference is made to the accompanying drawings, which form a part hereof, and in which there is shown by way of illustration a preferred embodiment of the invention. This embodiment does not represent the full scope of the invention. Thus, the claims should be looked to in order to judge the full scope of the invention.